1. Field of the Invention
The present invention relates to a retractor provided with an emergency locking system and a seat belt system adapted for safety belt device in various kinds of vehicles.
2. Description of the Prior Art
For safety belt devices for vehicles there has been known and widely used such type of locking mechanism which allows the webbing to be freely pulled out from and pulled back into the retractor so long as the vehicle is in its normal running state, but, when there occurs sudden change of the vehicle speed upon collision or the like, locks the webbing against the pull-out thereof so as to hold the passenger or driver for his safety in such emergency.
The known emergency locking mechanism of the type mentioned above are classified into two groups, that is, webbing pulling-out acceleration sensing type and vehicle acceleration sensing type. The emergency locking mechanism of the former type detects any sudden change of the vehicle speed caused by a collision or the like by sensing the change in speed of the pulling-out of the webbing. The emergency locking mechanism of the latter type detects it by directly sensing the change in speed of the vehicle itself.
The known retractor provided with the former type of emergency locking mechanism has that disadvantage that the locking mechanism may be actuated unnecessarily even when the webbing is pulled out from the retractor at a high speed, for example, at the time of wearing it on a passenger. This makes the handling of the safety belt device troublesome and inconvenient to the wearer. To overcome such problem it has been already proposed to hold the emergency locking mechanism in its inoperative position by actuating a holding means such as an electromagnet when no emergency locking is desired.
For the retractor provided with the latter mentioned type of emergency locking mechanism, namely the vehicle acceleration sensing type of emergency locking mechanism, however, there has been given almost no consideration to the problem of keeping the emergency locking mechanism in its inoperative position. This is because the retractor is usually mounted on a part of the vehicle such as the body of the vehicle. But, in case of a passive type safety belt system to which the passenger is forcedly fastened irrespective of his will, the retractor must be mounted on a movable part of the vehicle such as a door or the like. In this case, there is a possibility of the emergency locking mechanism being erroneously actuated during the movement of the movable part of the vehicle on which the retractor was mounted. On the other hand, if the retractor is provided with a mechanism for making the emergency locking mechanism inoperative when no emergency locking is necessary and if the retractor is mounted on a door of the vehicle, there will arise another problem in that the emergency locking mechanism may be made inoperative in emergency irrespective of the wearer's will when the door is opened for any reason in emergency.